Clamp



Patented Aug. 11, 1942V i i n CLAMP Frank c, weuae'e, kLes Angeles. Calif., assigner te' `Monogram Manufacturing Calif., a corporation of California Application November 21,1941, Serial locleims., (criss-ii)` l ,V ,I y

Y fnates the body orhousing` of `my clamp; which n is cylindricin form and has an end wall yprovided with-a central opening 'I. An'4 annular v recessA 8 provides means for mounting the body This invention has te de. withv clamps end -relates more particularly to clamps used as temporary 'means for clamping perforated sheets together in superposed relation, Withtheir per- -forations in register, while awaiting theA applicationof permanent rivets. This invention involves improvements upon those inventions disclosed and claimed in my copending applications Serial Number 387,198, filed April 7, 1941, and Serial Number 408,085, filed August 23, 1941.

A f well known dimculty with conventional clamps is that they scratch and mar the surface .l

of the sheets towhichth'ey are applied;v and' this-is particularly true of their use inY riveting` the sheets going tomake'up airplane fuselages,

.since those sheets are relatively softer than'thesteel of which the clamp body is made; Thus in applying and removing the clamp theexterior surface o1' the sheet `around the rivet hole is .in-

jured. It is therefore one of the principal ob I jects of this invention to overcome this serious shortcoming o`i' the prior art .by providing a clamp which embodies simple and eifectivemeans .l

for protecting the clamped surfacevoi the sheet.

Another object contemplated is Ythe 'provisionA of a clamp embodying emcient means for mounting such a protective member upon the clamp body. Another object is the provision of a clamp embodying a retaining or clamping member which is particularly conducive to facility andeconomy .r

of manufacture. Y 1 Y Additional objects and advantages are inherent in my invention( and how those as well as the `foregoing are accomplished willI become apparent from the following detailed description of'fa presently preferred embodiment thereof, for

' 280i the fingers are protractable and retractable throughopeningsl and lhave enlargedouter ends which purpose I shall refer to the accompanying y drawing,'in which:

Fig. 1 is a longitudinal sectional'.view ofA my clamp showing the position whichits partsoc- /cupy when the clamp is being applied;

Figs. 2 and 3 are elevational views showing they clamp in different positions of use, a part of the Y spring being broken awayin Fig. '3 for illustrative purposes; l i L i* Y Fig. 4 is a longitudinal section on llne 4-,4 of

Fis. 2; l Y Fig. 5 is a cross-section on line 5-5 of Fig. 1;

6 -is a cross-section on line B-Iof Fig. 1;`

and I Fig. 7 is a sectional view similar to Fig. f6 ybut showing a variational form.

In thedrawing, I show superposedtsheets .IS

having'perforations P, 'I'he numeral '5j desigf-V Co., Loskv Angeles,

No. 419,941V l.

in a clamp applying tool,'not shown. i

A retaining member generally designated by the numeral I0 is .reciprocally mountedk injthe' body and includes a stem I5, headed at I8,liav` ing a reduced inner end Il and an annulargroove` 1 I8 intermediate its ends. A pair of diametrically expansible retainingngers I 9 have', oppositely advantageous from the standpoint of facility 4,and economy of manufacture. 'Ihese retainingmembers arel usually made bythe swaging' process n' 1.V and it is "diiiicult to vforman integralxmember L having a rounded end portion I5, IB-.and the .forked outer sheetfengaging end; also they musi:V I

beflnade` toflt perforations of extremely small ydiameters suchv as ofthe order of rone-eighth inch or,` less, which further increasegthe manu#- `facturing diniculties. In, my described structure, however, the fingers I9 areformed separately Y from the stem portion'and may be readily made, vassembled and then'held in assembly simply by means of the surrounding spring. 'I'he outer ends 2.1providing'shoulder's 28 which engage thesheet S `farthest from the clamp `during the clamping operation to be described. 1 ,"Body 5 has an annular groove A3l) at its inner end into which the peripheral portion of an end cap 3i is crimpeclto securelyhold the caponthe body. Capl has a relatively large central openings: through whieh'an insulating member as projects, said insulator having an annular flange 35a coniinedby cap 3 Ir to prevent outward escape of the insulator through opening 32, and a spherical, smooth, non-abrasive 'outer surface 35h f adapted to bear against theouterisheet S when i the device is inclamping position. A-central holev 35e is lprovided through the' insulator tov slidably pass'fingers I9.y While, in the drawing, I have ,shown insulator as as being'made-orhard rubber, it" should be understood ythat other suitablenmaterials may be employed, the only lrequi-` sitebeing that thematerial of which the 'insu-A,

lator is made shall be non-abrasive with respect to the sheet against which it is to bear. For instance, these clamp bodies are usually made of hard steel in order to withstand the considerable stresses to which they are subjected and. in using the clamps to fasten aluminum or similar sheets, abrasion and injury result unless some positive protective means `is provided. In practice, I have found various well known plastics to be suitable for the material of the insulator.

A T-shaped spreader having a cross arm or anchor portion 40 and a central arm 40a is disposed between fingers I9, the anchor portion 40 being rotatably mounted in the circular recess 35d provided in the inner surface of the insulator. A guide ring 4l rests in recess 35d and surrounds the outer ends 26 of the fingers to prevent said fingers from spreading apart into wearing engagement with the insulator. The spreader is held against longitudinal movement between the end wall 6 of the body and the ring 4I. Thus as the fingers i9 slide longitudinally over the sides of the spreader, they vare diametrically expanded, but the spreader is free to rotate with the retaining member l to prevent twisting and injury to the retaining fingers during use of the clamp.

In operation, the body is operated and applied by means of a clamp applying tool such, forv instance, as shown in the copending application of Herman H. Helbush, Serial Number 411,879, filed September 22, 1941, and by means of this tool the retaining member is moved inwardly protract fingers i9. The central arm 40a of the spreader being shorter than the fingers I9, whenl spring 25 is thus fully compressed, the fingers I9 project from the body a suflicient distance be-` yond the outer end of the spreader (as shown in Fig. 1) to enable the outer ends of the fingers to be compressed together to insert their enlarged ends 21 through registeringperforationsr the shoulders 28 abut the sheet farthest froml the clamp, the sheets S being resiliently clamped between said shoulders and the spherical sheet engaging surface 35h of the insulator (position of Fig. 3). To remove the clamp, the spring is again compressed so that the fingers are protracted sufiiciently to enable the enlarged ends 21 to be compressed towards` each other and withdrawn through the perforations.

In Fig. 7, I show a modified form of my clamp in which the parts are as before described and are given like numerals, except that the cross arm 40 of the spreader is relatively longer and its outer end portions fit into transverseslots 50 provided in flange 35a of the insulator 35. Thus in this form of my clamp the spreader is not rotatable relative to the insulator. The insulator, however, is rotatable with respect to the body 5 andthe cap 3l.

While I have resorted to considerable detail for the purpose of making my invention understood, I wish it understood that within the broader scope of my invention, as defined by the appended claims, various modifications and adaptations may be made without departing from the spirit of the invention.

-of the body against the pressure of spring 25 to I claim:

1. A clamp for temporarily holding perforated sheets in superposed relation, including a body having a. sheet-engaging end portion and a retaining member reciprocally mounted in the body and comprising astem portion and a plurality of expansible fingers slidablel through said end portion to clamp said ysheets towards said sheetengaging end portion, said fingers having inner end portions embracing the stem exterior.

2. Al clamp for temporarily holding perforated metal sheets in superposed relation, comprising: a body having a substantially non-yielding plastic sheet-engaging end cap and a retaining member slidably mounted in and prcjectable from the body, said retaining member embodying means for clamping said engaged sheet against said end cap.

3. A clamp for temporarily holding perforated sheets in superposed relation, comprising: a bodyfhaving a substantially non-yielding plastic sheet-engaging end portion, a retaining member reciprocally mounted in the body and having a sheet-engaging portion, and spring means mounted in the body and operatively engaging the retaining member whereby to resiliently clamp said sheets between the sheet-engaging portion of the retaining member and said plastic sheet-engaging end portion of the body.

4. A clamp for temporarily holding perforated sheets in superposed relation, comprising: a cylindric body having an end wall presenting a central opening, an elongated retaining member reciprocally mounted in the body and having diametrically expansible prongs projectable through said opening whereby to be inserted through said -perforations a. spreader disposed Vbetween said prongs for expanding them into tral opening through said cap, an insulator overlying said anchor portion and having an annular flange confined between the cap and said end VWall and a medial portion projecting through said enlarged central opening, said medial portion presenting towards said sheets a convexed relatively non-abrasive sheet-engaging portion, and resilient means carried by the body and retractably engaging said retaining member whereby to clamp said engaged sheet against said yconvexed `sheet-engaging portion.

5. A clamp for temporarily holding perforated sheets in, superposed relation, comprising: a cylindric body, a retaining member reciprol cally mounted therein, said member including a stem and clamping fingers projectable at their outer ends from the housing for insertion through perforations in the sheets, the inner ends of said fingers having bifurcated portions embracing the stem, and means resiliently urging the retaining member into clamping position consisting of a coil spring longitudinally encircling the stem, said spring engaging said fingers whereby to hold them in position embracing the stem.

6.y A clamp for temporarily holding perforated sheets in superposed relation comprising: a cy lindric body, a retaining member reciprocally mounted therein, said member including a stem extending at its inner end into the body, an annular groove between' the ends of the stem.

said spring confining said inner end portions of the ilngers against lateral escape from the groove.

, 7. In aclamping device for holding perforated sheets in superposed relation, a body, aretaining member movably mounted in the body, said retaining member comprising an operating stem, a spring bearing against the stem, and a clamping element held in detachable engagement with the stem by the spring.

8. In a clamping device for holding perforated sheets in superposed relation, a body, a retainmg member movably mounted in the body, said vretaining member presenting radially expansible sheet clamping segments projeetable through an end of the body, an expander disposed between said segments, an end member rotatably disposed over said end of the body, said en d member presenting, an outer sheet engaging surface which is non-abrasive with respect tol the engaged sheets and a 'central hole'passing said segments, a transverse slot in the inner face of the' end member, said expander having an anchor portion engaging in said slot wherebyto be non-rotatable with respect to the Vend member,

and a ring secured to said-end of the body in position ,circumferentially' embracing the end member, said end member being rotatable with respect to the ring.

9. A clamp :or temporarily holding perforated sheets in superposed relation, including a body having a sheet-engaging end portion and a retaining member reciprooally mounted in the body and comprising a stem portion and arpluralityoi' expansible ilngers slidable through said end portion to clamp said sheets towards said .sheet-engaging end portion, each of said iingers having a lateral projection embracing thelstem viormable plastic sheet-engaging Iend member and a retaining member'slidably mounted in and projectable from. the body through said end member, said end member presenting a spherical sheet-engaging surface.

FRANK C. WALLACE. 

